1. Field of the Invention
The present invention relates to an X-ray imaging apparatus capable of positioning a device to irradiate an object with X-rays and imaging the object.
2. Description of the Related Art
Generally in X-ray photography, an X-ray generation unit and an imaging unit for receiving X-rays transmitted through an object as an X-ray image are arranged facing each other with the object interposed therebetween. In this case, a distance between the X-ray generation unit and the imaging unit is changed according to an attribute of the object and an imaging site, and respective centers of an X-ray irradiation field and an imaging plane are required to match with each other to prevent grid cut-off.
Examples of a method for recognizing a relative position between the X-ray generation unit and the imaging unit include irradiating a front surface of an imaging unit with visible light, as discussed in Japanese Patent Application Laid-Open No. 2006-305105, irradiating a front surface of an imaging unit, on which an X-ray non-transparent mark is arranged, with X-rays, as discussed in Japanese Patent Application Laid-Open No. 9-185140, and optically recognizing a marker arranged in an imaging unit, as discussed in Japanese Patent Application Laid-Open No. 2003-310591.
In positioning of the X-ray generation unit and the imaging unit, the imaging plane is required to be set right in front of an X-ray emitting plane in addition to carrying out distance adjustment and alignment of centers therebetween. This is because X-rays need to be incident on the imaging plane at right angles to prevent uneven irradiation.
In a general imaging room, a stationary X-ray generation unit of an overhead traveling type or the like and a stationary imaging unit which is fixed to a rack at a standing position or a lie position are installed in many cases. A portable imaging unit is also fixed to the rack when it is used for imaging.
Positioning under such an environment can be easily performed using a suspension unit or a guide of a stand whose vertical and horizontal directions are previously defined. In other words, a large-scale mechanical apparatus is required when the X-ray generation unit and the imaging unit are arranged at suitable relative positions.
Recent series of natural disasters around the world have indicated the importance of prompt diagnosis at the site. What is demanded now is an improvement in the convenience of carriage of and imaging by an X-ray imaging apparatus. This requires that the X-ray generation unit and the imaging unit can be positioned without requiring a large-scale mechanical apparatus.